Gastrointestinal Drugs

Question 1

Which cells secrete HCl acid?

Answer 1

parietal cells

Question 2

which cells secrete histamine?

Answer 2

ECL cells (which stimulate parietal cells)

Question 3

Waht’s the goal of GI drugs here?

Answer 3

Inhibition of gastric acid secretion

Question 4

H2 antagonists 
name one
what do
Indications
drug interactions
Care
don't confuse with

Answer 4

cimetidine

what: block histamine receptors on parietal cells (which secrete stomach acid)

Indications: GERD, peptic ulcer (PUD)

Drug ints: potentiates warfarin by inhibiting CYT P-450 liver enzyme

Care: impaired renal patients, confused elderly pts, take 1 hour before or after antacids

they’re not H1 receptors, which are the ones involved in allergic reactions

Question 5

Proton pump inhibitors (PPIs)
name one
waht do
indications
drug interactions
compare to H2 antagonists?

Answer 5

omeprazole (enteric-coated because it is not absorbed in teh stomach so don’t chew it!)

What: irreversibly bind to H+/K+/ATPase enzyme

Indications: GERD, peptic ulcer (PUD), esophagitis

Drug ints: warfarin potentiator

more effective than H2 antagonists

Question 6

Antacids
4 elements
name + hydroxide or carbonate
Drug interactions

Answer 6

Aluminum hydroxide - constipation

Magnesium hydroxide - diarrhea, contra is renal failure

(combine those two to get normal bowel function)

Calcium carbonate - constipation, kidney stones

Sodium bicarbonate - short duration, sodium problems (do not use with HF or hypertension)

Drug ints: reduces absorption of other drugs if given at teh same time by chelation (binding to metal ions to create insoluble complexes)

Question 7

Mucosal protection drugs

name two

Answer 7

sucralfate and misoprostol

Question 8

Sucralfate
Cytoprotective (means what)
forms a gel in ______ (high or low) pH?

Answer 8

Protects cells of the intestinal lining

gels in LOW pH (so don’t give with antacids)

constipation, chelation

Question 9

Misoprostol
what is it?
what do
contraindication

Answer 9

a synthetic prostaglandin (PGE1)

prostaglandins promote the production of mucous and bicarbonate for cytoprotection. also reduce acid secretion

reduce gastric effects of NSAIDs

do NOT use in pregnancy (contraction of smooth muscle, so it’s used to terminate pregnancies)

diarrhea

Question 10

Antidiarrheal drugs, name 3 groups

Answer 10

Opioids
Adsorbents
Anticholinergics

Question 11

Opioids
name one
mechanism
AEs

Answer 11

loperamide (imodium)

mechanism: increase transit time through bowel
this one is an opioid agonist but doesn’t enter CNS

AEs are typical opioid effects

Question 12

Adsorbents 
name one 
how?? 
AEs
Drug ints
Contra

Answer 12

bismuth subsalicylate

? maybe coat the walls of the GI tract? lol

AEs: constipation

Drug ints: reduce absorption

Contra: do NOT give to children (Reye’s syndrome)

Question 13

Anticholinergics
Name one
what do
AEs

Answer 13

atropine

what: antispasmodic, they decrease intestinal muscle tone and peristalsis

AEs classic anticholinergic effects (dry mouth, blurred vision, constipation, tachycardia)

Question 14

Laxatives
lots of kinds
overuse = ?
Adverse effects

Answer 14

overuse = lazy bowel (reduced muscular activity)

AEs: electrolyte imbalances
drink lots of water with all

Question 15

Bulk forming

name one

Answer 15

high-fibre substances (think metamucil)

methylcellulose

Question 16

Fecal softeners

Answer 16

docusate sodium

emollients and surfactants
promote water and fat in stools, but too much lubrication can be leaky

Question 17

Osmotic laxatives
what are?
two kinds (give one example of each as well)

Answer 17

non-absorbable compounds or salt solutions that draw water

Hyperosmotic - increase fecal water content (lactulose)

Salines - increase osmotic pressure in the intestine, push water out (magnesium hydroxide)

Question 18

Stimulants
name one
what do

Answer 18

senna

what: increase peristalsis and fluid secretion

Question 19

Antiemetics

most do what

Answer 19

antagonists - inhibit neurotransmitter action

Question 20

5-HT (serotonin) antagonist
name one
why?
AE

Answer 20

ondansetron
cancer chemotherapy (give 30 min to 3 hrs before)
AE dysrhythmia

Question 21

Dopamine antagonists (two kinds)
name one (of each)
why?
AE

Answer 21

antipsychotic (neuroleptic) - chlorpromazine
more severe vomiting

prokinetic (GI motility) - metoclopramide
stimulate peristalsis

AE movement disorders

Question 22

Anticholinergics
name one
why?
AE

Answer 22

scopolamine (has access to the CNS)

motion sickness

anticholinergic effects

Question 23

Antihistamines
name one
what do
AE

Answer 23

dimenhydrinate (combo of diphenhydramine and chlorotheophylline)

H1 receptor antagonists

AE sedation